The present invention generally relates to a coaxial resonator and more particularly, to a dielectric material coaxial resonator employing a dielectric material block, and provided with an improved resonance frequency adjusting mechanism.
Commonly, as shown in FIG. 1, a 1/4 wavelength coaxial TEM resonator includes a dielectric material member 3, for example, of a titanium oxide group ceramic dielectric material or the like provided between an inner conductor 1 and an outer conductor 2. More specifically, a material having superior high frequency electrical conductivity and having a favorable adhesion with respect to the dielectric material member 3, for example, silver paste is baked onto the inner wall surface i.e. the peripheral surface of a through-opening 5 formed in the dielectric material member 3 and the outer wall surface of said dielectric material member 3 to form the inner conductor 1 and the outer conductor 2, with said inner and outer conductors 1 and 2 being short-circuited by an electrode or conductive layer 4 formed on one end face of the dielectric material member 3, thus providing a short-circuited end 3a on said one end face and an open end 3b on the other end face of said dielectric material member 3.
Conventionally, for a resonance frequency adjusting mechanism of a 1/4 wavelength coaxial TEM resonator of the above described type, there has generally been known an arrangement in which a sleeve 6 formed with an internally threaded portion 6s therein is fitted into the through-opening 5 against the inner conductor 1 at the open end 3b of the dielectric material member 3, and an adjusting screw 7 of a metallic material is threaded into the internally threaded portion 6s so the resonance frequency can be adjusted by turning or vertically moving the adjusting screw 7.
However, in the resonance frequency adjusting mechanism for the dielectric material coaxial resonator as described above, since the adjusting screw 7 is threaded into the internally threaded portion 6s at the inner side of the open end 3b of the dielectric material member 3 at which the current is concentrated, there has been a drawback that the path through which the ground current flow is altered, with a consequent instability of the resonance frequency due to side play, etc. before the adjusting screw 7 has been fixed to the internally threaded portion 6s by a bonding material or the like.